This study proposes to use a simple, noninvasive method that assesses intestinal permeability to two sugar substances (lactulose and mannitol) to (1) demonstrate a difference in intestinal function between HIV-infected and HIV-uninfected children, and (2) evaluate the effect of growth hormone on the intestinal barrier function in HIV-infected children with growth failure. Underlying this proposal are the hypotheses that HIV-infected children with growth failure have decreased intestinal barrier function, and that growth hormone may improve mucosal intergrity in these children. Results from this study will improve our understanding of Acquired Immunodeficiency Syndrome (AIDS) in children, add to our present knowledge on the effects of growth hormone on gastrointestinal function, and confirm the value of the permeability test in the evaluation of gastrointestinal function in HIV-infected children.